Early
Phase
Type I (anaphylactic) reaction results in release of histamine and
other substances, resulting in inflammatory manifestations of allergy
Late Phase
Other factors including eosinophil activity, result in release of
chemical mediators which produce cytotoxic and other effects and further
aggravate the inflammatory response

- Cetirizine
is a highly effective antihistamine, but is more suited for preventing
attacks of allergic rhinitis
- Pseudoephedrine relieves nasal congestion thus producing symptomatic
relief
- This combination will do both
- relieve symptoms and prevent attacks
- thus is an ideal agent
- In perennial rhinitis, nasal congestion is often a consistent feature.
A combination such as this will be particularly useful here